The new head of the U.N. World Food Program is visiting Darfur, where more than 200,000 people have been killed and millions have been displaced by fighting between African rebels and Arab militias known as janjaweed, which are backed by government troops.

The war in Darfur in western Sudan has been going on for four years now. A peace deal was signed last year, but fighting continues, despite the presence of some 7,000 African Union troops who have been deployed in Darfur for the past year.

Sudan's central government in Khartoum is reluctant to allow foreigners access to the territory; it has accused aid workers of inflating the crisis.

Attacks on relief workers in Darfur have increased, with 12 aid workers killed last year. Melissa Block talks with NPR's Gwen Thompkins, who visited the Darfur camps for the displaced and health clinics along with U.N. World Food Program Executive Director Josette Sheeran.